The present invention relates to a method for producing character-bit patterns to be printed in a dot matrix form.
FIG. 17 shows storage regions in a conventional font memory for storing character-bit patterns. The reference numeral 1 indicates a font memory. FIG. 18 illustrates how the character-bit patterns stored in the font memory 1 are planted in a bit map memory indicated by the reference numeral 2. The font memory 1 includes a plurality of storage regions Q1, . . . , Qm, . . . , Qn, . . . (hereinafter to be generally referred to by the reference character Q), each corresponding to an address which is related to a character to be planted. In each storage region Q, there is stored a bit pattern for a character to be planted. The memory-capacities of the storage regions Q are the same, and the capacity is not less than that required for a character-bit pattern whose number of bits is the greatest of all the character-bit patterns.
In a conventional font memory, for example as depicted in FIG. 17, the bit pattern for the character or letter 37 A" is stored in the storage region Q1, and the bit pattern for the character "e" is stored in the storage region Qm. Likewise, the bit pattern of the character "g" is stored in the storage region Qn. When the character 37 A" is specified to be planted, a corresponding address designates the storage region Q1, and the whole of storage region Q1 is read or scanned to plant the bit pattern for the letter 37 A" on the bit map memory as in FIG. 18. In the same way, when the characters "e" and "g" are specified, corresponding addresses designate storage regions Qm and Qn, respectively. Then the whole of storage regions Qm and Qn are scanned and, as a result, the bit patterns for the characters "e" and "g" are planted in the bit map memory as illustrated in FIG. 18.
In the font memory 1 according to the above prior art, each storage region is designed to have a memory-capacity which is not less than the memory-capacity required to store a bit pattern for the character having the greatest number of bits of all the characters. Accordingly, the font memory 1 leaves a wasted blank area where no bit pattern is stored, resulting in a poor utilization of the font memory.
An object of the invention is to improve the utilization of a font memory by making sure that, in storage regions of a font memory for storing character-bit patterns, a blank with no character-bit is not produced outside the character-bit pattern at least in the direction perpendicular to the direction of scanning of the character-bit pattern.
Another object of the invention is to reduce the scanning time required to plant a character-bit pattern in the bit map memory.
Still another object of the invention is to improve the utilization of a font memory by further reducing to a minimum the wasted blank area in a storage region used for storing the bit pattern of the character.